This application relates to the art of can manufacture and, more particularly, to curing of coatings applied to longitudinal seams on can bodies.
The application is particularly applicable for use in curing coatings applied to welded longitudinal seams of cylindrical can bodies and will be particularly described with reference thereto. However, it will be appreciated that the invention has broader aspects and may be used for localized longitudinal heating of other bodies and may be used for purposes other than curing coatings.
Can bodies are commonly manufactured by taking flat rectangular metal blanks having a coating on one surface thereof except in the area at the edges of the blanks which will be overlapped and welded because welding requires absolutely clean metal for good bonding. The welded longitudinal seams are then coated with either liquids or powders to protect the contents of the ultimate containers from contamination by bare metal and to protect the integrity of the containers themselves from possible damage by the container products.
It is very common to use coatings such as vinyl, epoxys and phenolics in liquid form and to apply such coatings by spray heads at suitable stations on a machine. Air drying of the coating is very time consuming and often does not result in a highly protective, impervious coating. It would be desirable to have an apparatus for heating the longitudinal seams in a highly efficient manner for heat curing coatings applied to the welded longitudinal seams.